389

Trimming of Blocks for Microscopic Study

The following description of microscopic sections represents a general guideline for an appropriate sampling of autopsy tis-sues. However, the number, site, and size of sections should be tailored to the individual case.

Since the morphology of fetal tissues changes throughout gestation, it is important for the pathologist to become famil-iar with their normal appearance in order to evaluate possible abnormalities. Therefore, even when organs are grossly normal or maceration is present, sections should be obtained in the same manner.

I. Head and neckA. Tongue, Hyoid Bone, and Epiglottis

Sagittal section of base of tongue along midline including foramen cecum.B. Neck Soft Tissues, Larynx, Upper Esophagus, Thyroid, and Parathyroid Glands

Serial cross-sections at 3-mm intervals of entire larynx and thyroid gland.C. Submandibular Salivary Gland

II. Respiratory systemA. Trachea (in patients who have been ventilated)

Longitudinal coronal section of distal trachea, carina, and main stem bronchi.B. Lungs

One section of each lobe including the hilum and major bronchus and extending into peripheral lung and pleura.

III. Cardiovascular SystemA. Heart

1. Normal heart: one longitudinal section of each ventricle including a papillary muscle, full-thickness free wall, atrioventricular valve, and base of atrium.

2. Anomalous heart: sections of right and left ventricles along cuts made to examine the chambers. Gross specimen is preserved for teaching and should remain as intact as possible.

B. Aorta (if considered necessary)

IV. Digestive systemA. Esophagus and Stomach

1. Longitudinal section of distal esophagus and proximal stomach across the G–E junction and cross-sections of distal and proximal esophagus.

2. Cross-section(s) of body of stomach.3. Longitudinal section of antrum and duodenum across the pylorus.

B. Small and Large BowelRandom cross-sections if no lesions are seen. Include ileocecal valve and appendix.

C. RectumLongitudinal section of the rectum with anal skin, if present. A cross-section of distal end of rectum and attached prostate or vagina is also acceptable.

D. LiverOne section from each lobe (gallbladder can be included to identify right lobe).

E. PancreasOne section of head including adjacent duodenum and one or two cross-sections of body and tail.

Appendix

L.M. Ernst et al. (eds.), Color Atlas of Fetal and Neonatal Histology,DOI 10.1007/978-1-4614-0019-6, © Springer Science+Business Media, LLC 2011

390 Appendix

V. Urogenital systemA. Kidneys

One section of each kidney including at least one well-oriented medullary pyramid with papilla and overlying cortex (renal lobe).

B. BladderA strip of bladder mucosa and wall. Include cross-section of prostate if not already sampled.

C. UterusCross-section of fundus and longitudinal midsagittal section of cervix and vagina (if no septation is seen on cross-section).

D. OvariesLongitudinal section including hilum and broad ligament.

E. TestesLongitudinal section including epididymis.

VI. Lymphoreticular systemA. Spleen and Thymus

One section of each.B. Lymph Nodes

Sample as necessary according to gross findings. For routine sampling of lymph nodes the small bowel mesentery provides a good source.

VII. Endocrine systemA. Thyroid and Parathyroid Glands

Usually not separated from larynx and trachea. See head and neck section.B. Adrenal Glands

One cross-section of each gland perpendicular to long axis for better orientation of cortex and medulla.C. Pituitary Gland

Usually submitted in toto within the sella turcica. If larger, one transverse section showing anterior and posterior lobes is desirable.

VIII. Musculoskeletal systemA. Psoas and Diaphragm

Longitudinal and cross-sections of each.B. Rib and Vertebral Body

Longitudinal section of rib including the costochondral junction and midsagittal section of vertebral body. Decalcify very gently and for a minimal period of time. Do not decalcify overnight.

391Index

AAccessory spleens, 260Adrenal cortical rests, 139Adrenal corticotropin hormone (ACTH), 234Adrenal cytomegaly, 210Adrenal gland

adrenal cytomegaly, 210areas and zones, 203calcifications, 211definitive cortical zone, adenoid change, 211embryology, 203extramedullary hematopoiesis, 211heterotopic adrenal tissue, 209–210histology

capsule, 204cortex, 205medulla, 208at 12 weeks gestation, 204, 206at 17 weeks gestation, 204at 20 weeks gestation, 204, 206at 26 weeks gestation, 204at 35 weeks gestation, 205, 206at 39 weeks gestation, 206

Adventitia, 40, 118, 119Alveolar stage, 32–33Alveoli, 23, 26Anal canal

less than 14 weeks, 5914 to 30 weeks, 60, 63

Anitschkow nuclear structure, 6Anterior pituitary gland

ACTH, 234histological feature of, 234Rathke cleft cyst, 234, 236at 26 weeks gestation, 234, 235at 35 weeks gestation, 234–236

Antral follicles, 176Aorta, 15Apocrine metaplasia, 358Appendix

less than 14 weeks, 5914 to 30 weeks, 59–63

Auerbach’s plexus, in small intestine, 57

BBasal ganglia

at term, 314–315at 8 weeks, 289at 14 weeks, 291at 22 weeks, 297at 27 weeks, 301at 32 weeks, 305–306at 35 weeks, 310–311at 2 years postnatal, 317–318

Basal platecomponents of, from intervillous space to endometrium, 376layers, 375, 376

maternal vascular remodeling, 375at term, 375–37814 weeks gestation, 377at 23 weeks gestation, 377

Basophils, 234Bilateral bulbourethral glands, 163Biliary tract

hepatic duct, transverse section of, 73, 76at 16-weeks, 73, 74at 17-weeks, 73, 74at 24-weeks, 73, 75at 36-weeks, 73, 75

Bipotential genitourinary tractbipotential gonads, 100, 101mesonephric and paramesonephric ducts, 102, 103paramesonephric duct, in male, 102

Bipotential gonads, 100, 101Bipotential paramesonephric ducts, 102, 103Blood islands, 273Blood supply, lymph nodes, 262Blood vessels

aorta, 15ductus arteriosus, 16–17umbilical vein, 17

Bonecell types in

osteoblasts, 332osteoclasts, 333osteocytes, 333osteoprogenitor cells, 332

embryologylong bone ossification, 324, 325lower limb, 324, 326metacarpal bone ossification, 324, 325ossification, in fetus, 324, 327paraxial mesoderm, 323somites, skeletal and muscular derivatives of, 323, 324somitic mesoderm, 323sternum, 323–324

formation, typesendochondral ossification, 334–335membranous ossification, 336

histologycell types, 332–333formation, 334–336structure, 328–329types, 330–331

organic components, 330structure of

cortical bone, 328–329medullary canal, 329periosteum, 328

types oflamellar bone, 330woven bone, 331

Bone marrowembryology, 273–274

Index

392 Index

during fetal life, 275hematopoiesis, 273hemophagocytosis, 280–281histology, 274–280myelopoiesis

dyserythropoiesis, 278–279erythropoiesis, 278granulopoiesis, 277hematogones, 279–280lymphopoiesis, 279–280megakaryopoiesis, 279monopoiesis, 277

structure of, 276trilineage hematopoiesis, 276at 19 weeks gestation, 275at 24 weeks gestation, 275at 32 weeks gestation, 276at 41 weeks gestation, 276

Brain. See Central nervous system (CNS)Brainstem, 290Branching morphogenesis, 163Bronchi, 23, 25Bronchioles, 23, 26Bronchus-associated lymphoid tissue (BALT), 23, 26Brunner’s glands, 54–55, 58

CCalcification, yolk sac, 387Calcitonin immunohistochemistry, 222Canalicular stage, 29–30Capsule, fetal spleen, 251Caudal gonadal ligaments, 98–100Central nervous system (CNS)

embryology, 285–286first trimester

brainstem and cerebellum, 290cerebral cortex, 288–289neural tube, 288spinal cord, 290

histologyfirst trimester, 288–290myelination gliosis, 288neurogenesis, 287second and third trimesters, 290–313

postnatalbasal ganglia, 316–318cerebellum, 316, 318frontal cortex, 316occipital cortex, 316spinal cord, 316, 319white matter, 316, 317

second and third trimesters13 to 15 weeks, 290–29216 to 18 weeks, 293–29519 to 22 weeks, 295–30329 to 33 weeks, 304–30734 to 38 weeks, 308–313

sulcal development, 287term

basal ganglia at, 313–315cerebellum, 313, 315cerebral cortex at, 313, 314hippocampus at, 313, 315white matter at, 313, 314

Centroacinar cells, 80, 81Cerebellum

in first trimester, 290postnatal, 318at term, 315at 14 weeks, 292at 17 weeks, 29520 and 21 weeks gestation, 29830 and 31 weeks, gestation, 307at 35 weeks, 311–312

Cerebral cortexat postnatal, 316at term, 313, 314at 8 weeks, 289at 14 weeks, 291at 17 weeks, 293at 20 weeks, 296at 21 weeks, 296at 25 weeks, 300at 32 weeks, 304–305at 35 weeks, 308–309white matter, 309–310

Chorionic plate, 373–374Choroid plexus

at 8 weeks, 289at 17 weeks, 294at 32 weeks, 306

Conduction system, heart, 13–14Congenital blood cyst, 10, 12Congenital erosion, 193Connective tissue trabeculae, 242–243Cordae tendineae, 10Corpus striatum, 294Cortical bone, 328–329Cowper’s glands. See Bilateral bulbourethral glands

DDefinitive urogenital sinus, 117Dichorionic diamnionic twin placentas, 385Diencephalon, 286, 292Ductus arteriosus, 16–17Ductus deferens. See Vas deferensDuctus venosus, 68, 69Duodenum, 54–55, 58Dyserythropoiesis, 278–279

EEctodermal ring, 97, 98Embryology

adrenal gland, 203bone

long bone ossification, 324, 325lower limb, 324, 326metacarpal bone ossification, 324, 325

393Index

ossification, in fetus, 324, 327paraxial mesoderm, 323somites, skeletal and muscular derivatives of, 323, 324somitic mesoderm, 323sternum, 323–324

bone marrow, 273–274epididymis

efferent ductules and head of, 143–144mesonephric duct, 143urogenital union, 144

fallopian tubes, 181of genitourinary tract

bipotential, 101–103primitive, 95–100

lymph nodes, 261mammary gland, 347–348ovary

central zone and peripheral zone, 173–1747th week postfertilization, 1738th week postfertilization, 174

palatine tonsil, 267parathyroid gland, 225pituitary gland, 231–232placenta

amnionic and chorionic cavities, formation of, 364–365early placental development, 363, 364primary, secondary, and tertiary villi, 364, 365

prostate gland, 163of salivary glands, 87seminal vesicle, 157skeletal muscle, 337–338of spleen, 251testis

primordial germ cells, maturation process, 122seminiferous tubules, 121tunica albuginea, 122

thymus gland, 241thyroid gland, 213uterus, 187vagina, 195vas deferens, 153

Embryonic skeletal muscle, 338–339Embryonic stage, lung, 27Endocardium, 8–9Endochondral ossification, 334–335Endocrine cell nucleomegaly, 82, 84Endocrine pancreas, 82–84Endometrium

at 28 and 32 weeks, 190at 21 weeks, 190at 35 weeks, 191

Endomysium, 343Epicardium, 5–6Epididymis

coni vasculosi, 147embryology

efferent ductules and head of, 143–144mesonephric duct, 143urogenital union, 144

fetal histology, 145coni vasculosi, 22 weeks gestation, 147at 17 weeks gestation, 146at 22 weeks gestation, 147–148at 34 weeks gestation, 149–150at 39 weeks gestation, 150–152

function, 143histology, 144

EPM. See Extraplacental membranes (EPM)Epoophoron, 180Erythropoiesis, 278Esophagus

Auerbach’s plexus in, 46ectopic gastric cardiac in, 44less than 14 weeks, 41–43pyloric mucosa in, 4414 to 30 weeks, 43–4430 to 40 weeks, 45–46at 34 weeks, 45at 35 weeks, 46

Exocrine pancreas, 80–81Extramedullary hematopoiesis, 211Extraplacental membranes (EPM)

decidua parietalis, 367–368reactive amnionic changes, 366, 368at term, 366, 367at 15 weeks gestation, 366, 367at 32 weeks gestation, 366, 367

FFallopian tubes

anatomic organization, 181embryology, 181histology, 182–184muscularis (myosalpinx) layer

23 weeks, 18332 weeks, 18438 weeks, 184

serosa layer19 weeks, 18221 weeks, 18338 weeks, 184

tubal mucosa layer19 weeks, 182, 18321 weeks, 18323 weeks, 182

Fetal Leydig cellsdefinition, 121maturation, 123regression and dedifferentiation, 128

Fetal muscle developmentmuscle fibers, full-term neonate, 339, 342at term, 341at 17 weeks gestation, 339–340at 23 weeks gestation, 340

Fetal pulmonary developmental stagesalveolar stage, 32–33canalicular stage, 29–30embryonic stage, 27

394 Index

pseudoglandular stage, 28–29saccular stage, 31–32

Fetal spermatogonia, 121Fetal spleen. See SpleenFetal vs. adult myocardium, 4Fetus papyraceous, 386–387Follicles, 176Follicular atresia, 179Folliculogenesis

Graafian follicle, 32 weeks gestation, 178primary follicles, 30 weeks gestation, 177primordial follicles, 28 weeks gestation, 177secondary or preantral follicles

32 weeks gestation, 17738 weeks gestation, 178

tertiary or antral follicles, 38 weeks gestation, 17828 weeks gestation, 177

Foramen ovale, 3Forebrain, 286Fused paramesonephric ducts, 195

GGastrointestinal tract

definition and function, 39embryology, 39histology

anal canal, 59–60, 63–64appendix, 59–63esophagus, 41–46large intestine, 59–61small intestine, 52–58stomach, 47–51timing and sequence, developmental events, 40–41wall, organization of, 40

segments, 39Genitourinary tract

bipotentialbipotential gonads, 100, 101mesonephric and paramesonephric ducts, 102, 103paramesonephric duct, in male, 102

phases of, 95primitive

described, 95ectodermal ring, 97, 98inguinal region and caudal gonadal ligaments, 98–100mesonephros and mesonephric duct, 96–97

Graafian follicle, 176Granulopoiesis, 277Gut-associated lymphoid tissue

in appendix, 61in small intestine, 57

HHassall’s corpuscles, 248Heart

embryology, 3–4histology

endocardium, 8–9epicardium, 5–6fetal vs. adult myocardium, 4

myocardium, 6–8pericardium, 5

specialized structuresconduction system, 13–14papillary muscles and cordae tendineae, 10valve leaflets and cusps, 10–13

Hematogones, 279–280Hematopoiesis

bone marrow, 273extramedullary, 211fetal spleen and, 260liver, 70, 72lymph nodes and, 265pancreas, 84trilineage, 276

Hemophagocytosis, 265, 280–281Hemosiderin, 70, 73Hepatic lobule

endothelial sinusoids, 69, 71hematopoiesis, 70, 72hemosiderin, 70, 73hepatocyte cords, 69, 70Kupffer cells, 69–7020-weeks, 69, 71

Hepatic vasculature, development of, 68–69Hepatobiliary morphogenesis, 67–68Heterotopic adrenal tissue, 209–210Hilus cells, 179Hippocampus

at term, 315at 17 weeks, 293–294at 21 weeks, 296at 22 weeks, 297at 35 weeks, 310

IInguinal region, 98–100Interlobular stroma, 358Intra-acinar pulmonary arterioles, 33Intracytoplasmic hyaline globules, 55Intrapulmonary karyorrhectic cells, 34Intrapulmonary squamous cells, 34–35Intrathryroidal inclusions, 223

JJuxtaglomerular apparatus, 108, 113

KKaryorrhectic cells, intrapulmonary, 34Kidney

embryologycommon excretory duct, 105eighth week, 106–107seventh week, 106sixth week, 105–10619 weeks, 107

histologycollecting ducts, 108, 115glomeruli, development of, 108, 111, 112juxtaglomerular apparatus, 108, 113

395Index

medulla, 108, 114–115nephrogenesis, 108, 111–112nephrogenic zone, 107–108, 110proximal convoluted tubules, 108, 113renal cortex, 107, 109renal lobe, 107renin-expressing cells, 108, 114tubular growth and maturation, 108, 113

at 19 weeks gestation, 107Kupffer cells, 69–70

LLamellar bone, 330Lamina propria, 118, 119Large intestine

14 to 30 weeks, 59–6130 to 40 weeks, 64at 12 weeks, 59

Liverembryology

development mechanisms, 67–68hepatic morphogenesis, 68hepatic vasculature, development of, 68–69

hematopoiesis in, 70, 72hemosiderin in, 70, 73histology

biliary tract, 73–76hepatic lobule, 69–73

Long bone ossification, 324, 325Loops of Henle, 106, 108, 114Lung

embryology, 22formation, stages of, 21–22histology

fetal pulmonary developmental stages, 27–33postnatal pulmonary, 23–26

intra-acinar pulmonary arterioles, 33intrapulmonary karyorrhectic cells, 34intrapulmonary squamous cells, 34–35

Lymphatics, 264. See also Lymph nodesLymph nodes

embryology, 261and hematopoiesis, 265hemophagocytosis, 265histology, 262–265lymphatics, 262mesenteric, at 34 weeks gestation, 262–264vs. parathyroid gland, 225–22641 weeks gestation, 262, 264–265at 19 weeks gestation, 262–263

Lymphopoiesis, 279–280

MMammary gland

development stages, 347ducts

apocrine metaplasia, 358appearance of, buds, 350, 351atypical giant cells, interlobular stroma, 358complex branching, 355

early branching morphogenesis, 353exaggerated cystic change, 359near-term hyperplasia, early regression, 358neonatal hyperplasia and secretion, 357neonatal regression, 359penetratoin, 352primary ducts, 356progressive branching morphogenesis, 354smooth muscle, specialized mesenchyme, 351

embryology, 347–348histology, 348–350mammary band, 347mammary crest, 347–348nipple, 16 weeks gestation, 348, 349witches’milk, 347

Medullaadrenal gland, 208–209kidney, 106–108, 114–115thymus gland, 248

Medullary canal, 329Megakaryopoiesis, 279Membranous ossification, 336Membranous septum, 4Mesenteric lymph nodes, 262–264Mesonephric ducts, 96–97, 102, 103Mesonephric remnants duct, 180Mesonephros ducts, 96–97Metacarpal bone ossification, 324, 325Monochorionic diamnionic twins, 385Monopoiesis, 277Mucosa, 40Müllerian ducts, 102, 103Multiple gestations, 385–386Muscle development

early histogenesis, 338–339fetal, 339–342postnatal, 342

Muscle spindles, 343–344Muscularis propria, 40, 119–120Myelination, 288Myelopoiesis

dyserythropoiesis, 278–279erythropoiesis, 278granulopoiesis, 277hematogones, 279–280lymphopoiesis, 279–280megakaryopoiesis, 279monopoiesis, 277

Myocardium, 6–8Myometrium, 189, 190

NNephrogenesis, 105, 108, 111–112Nephron

diagrammatic fate map of, 106at eighth week, 107

Nesidioblastosis, 79, 83Neural tube, 288Nodular splenic heterotopia, 84, 85Nucleated red blood cells (NRBC), 379

396 Index

OOogonia, 174Osteoblasts, 332Osteoclasts, 333Osteocytes, 333Osteoprogenitor cells, 332Ostium primum, 3Ostium secundum, 3Ovary

embryologycentral zone and peripheral zone, 173–1747th week postfertilization, 1738th week postfertilization, 174

follicular atresia, 179folliculogenesis

follicles, maturational stages, 28 weeks gestation, 177Graafian follicle, 32 weeks gestation, 178primary follicles, 30 weeks gestation, 177primordial follicles, 28 weeks gestation, 177secondary or preantral follicles

32 weeks gestation, 17738 weeks gestation, 178

tertiary or antral follicles, 38 weeks gestation, 178hilus cells, 35 weeks gestation, 179histology

oocytes and follicles, 24 weeks gestation, 176oogonia, 16 weeks gestation, 176stroma, 19 and 35 weeks gestation, 175surface epithelium, 21 weeks gestation, 174tunica albuginea (TA), 28 weeks gestation, 17519 weeks gestation, 174

mesonephric duct remnants, 19 weeks gestation, 180rete ovarii, 180

PPalatine tonsil

embryology, 267histology, 267–270with intraepithelial lymphocytes, 268, 270location of, 267at term, 268, 270at 16 weeks gestation, 267, 268at 17 weeks gestation, 267–269at 21 weeks gestation, 267, 269at 27 weeks gestation, 267, 269–270

Pancreasembryology, 79–80histology

endocrine pancreas, 82–84exocrine pancreas, 80–81hematopoiesis, 84lymphoid tissue, 84nodular splenic heterotopia, 84, 85pancreatic stroma, 80small bowel pancreatic heterotopia, 84, 85

Papillary muscles, 10Parafollicular C cells

fetal thyroid gland, close-up view, 222lateral lobe, thyroid gland, 222

Parathyroid glandembryology, 225histology

ectopic, undescended thymic lobule, 229vs. lymph node, 225–226term gestation, 228at 18 weeks gestation, 227at 24 weeks gestation, 227at 34 weeks gestation, 228at 39 weeks gestation, 228

vs. lymph node, 225–226Paraxial mesoderm, 323Pericardium, 5Perimysium, 343Periosteum, 328Perivillous fibrin, 379Pituicytes, 237Pituitary gland

anteriorACTH, 234histological feature of, 234Rathke cleft cyst, 234, 236at 26 weeks gestation, 234, 235at 35 weeks gestation, 234–236

embryology, 231–232histology, 232–237posterior, 237

Placentaanatomy of, 366basal plate

components of, from intervillous space to endometrium, 376layers, 375at term, 375–37814 weeks gestation, 377at 23 weeks gestation, 377

chorionic plate, 373–374definition, 363dichorionic dividing membrane, 386embryology

amnionic and chorionic cavities, formation of, 364–365early placental development, 363, 364villous development, 364, 365

extraplacental membranesdecidua parietalis, 367–368reactive amnionic changes, 366, 368at term, 366, 367at 15 weeks gestation, 366, 367at 32 weeks gestation, 366, 367

fetus papyraceous, 386–387histology, 366–385monochorionic dividing membrane, 386multiple gestations, 385–386twin dividing membranes, 385umbilical cord

allantoic remnants, 369, 372arteries, 368, 370components of, 368vein and artery, at term, 371vitelline duct remnant, 369, 371–372

397Index

at 16 weeks gestation, 369, 370at 24 weeks gestation, 369at 35 weeks gestation, 370at 36 weeks gestation, 369Wharton’s jelly, 368, 369

villous parenchymachorionic villi, 381, 383–384gestational age, types and characteristics by, 380mesenchymal villi, 378nucleated red blood cells, 379perivillous fibrin, 379placental tissue, at 6 weeks, 380–381placental villi, 381–385stem villi, 378syncytiotrophoblastic knots or syncytial knots, 379terminal villi, 379types and characteristics, 378, 379

yolk sac remnant, 387Posterior pituitary gland, 237Postnatal cerebellum, 318Preantral follicles, 176Primary follicles, 176Primordia, 347–348Primordial follicles, 176Prostate gland

embryology, 163epithelial elements

ejaculatory ducts, 17 weeks gestation, 165prostatic ducts, squamous metaplasia of, 166prostatic utricle, verumontanum, 166squamous metaplasia, prostatic urethra with, 166verumontanum, 17 weeks gestation, 16517 weeks gestation, 16520 weeks gestation, 16724 weeks gestation, 167, 16829 weeks gestation, 16834 weeks gestation, 16939 weeks gestation, 169, 170

histology, 164male genital system, accessory glandsprostatic utriclepurpose, 163stromal elements, 17017 weeks gestation, 164

Prostatic utricle, 163Pseudoglandular stage, 28–29Pulmonary acinus, 23, 24

RRadial glia, 287Rathke cleft cyst, 234, 236Rathke’s pouch, 231Red pulp, in spleen, 260Renal lobe, 107Rete ovarii, 180Rete testis

15 weeks gestation, 12426 weeks gestation, 131, 13239 weeks gestation, 133–13441 weeks gestation, 135

Rostral neural crest cells, 41

SSaccular stage, 31–32Salivary glands

embryology, 87submandibular gland, histology of

at 16 weeks, 88at 19 weeks, 88, 89at 23 weeks, 88, 89at 27 weeks, 88, 90–91at 35 weeks, 88, 91at 41 weeks, 88, 92

Secondary follicles, 176Seminal colliculus. See VerumontanumSeminal vesicle

appearance of, 157–158embryology, 157fetal development

17 weeks gestation, 15824 weeks gestation, 15929 weeks gestation, 159–16034 weeks gestation, 16038 weeks gestation, 161

functions, 157histology, 157–161

Seminiferous tubuledefinition, 12115 weeks gestation, 12517 weeks gestation, 12621 weeks gestation, 12926 weeks gestation, 13139 weeks gestation, 132, 13341 weeks gestation, 135

Sertoli cells, 121Skeletal muscle

early histogenesis, 338–339embryology, 337–338fetal muscle development, 339–342histology, 338–342muscle spindles, 343–344postnatal muscle development, 342supporting framework, 343

Small bowel pancreatic heterotopia, 84, 85Small intestine

Auerbach’s plexus in, 57Brunner’s glands, 54–55, 58duodenum, 54–55, 58gut-associated lymphoid tissue in, 57intracytoplasmic hyaline globules, 55less than 14 weeks, 52–5314 to 30 weeks, 54–5730 to 40 weeks, 58

Solid cell nests. See Ultimobranchial body remnantsSomitic mesoderm, 323Spermatic duct. See Vas deferensSpinal cord. See also Central nervous system (CNS)

in first trimester, 290at 14 weeks, 292at 19 weeks, 295

398 Index

at 20 weeks, 299at 22 weeks, 299at 25 weeks, 303at 30 weeks, 307at 35 weeks, 312–3132 years postnatal, 319

Spleenaccessory, 260capsule, 251embryology, 251and hematopoiesis, 260histology of, 251–260postnatal, 259red pulp, 260at term, 259–260vascular tree, 252at 16 weeks gestation, 252, 254at 21 weeks gestation, 255at 23 weeks gestation, 256at 24 weeks gestation, 256at 32 weeks gestation, 257at 35 weeks gestation, 258–259white pulp

follicular dendritic cells, 252, 253splenic lymphoid and sinus development, 252, 253splenic marginal zone, 253T-and B-lymphocytes, 252, 255–256

Squamous cells, intrapulmonary, 34–35Stem villi, 373, 374, 378–380Stomach

esophago-gastric junction, 48gastric cardiac mucosa, 49gastric pyloric mucosa, 51

at 12 weeks, 49at 24 weeks, 49at 35 weeks, 51

less than 14 weeks, 47–49muscularis propria, 47, 49oxyntic mucosa, 5114 to 30 weeks, 49–5030 to 40 weeks, 51

Stress involution, thymus gland, 249–250Stroma, thyroid gland, 222Submandibular gland

at 16 weeks, 88at 19 weeks, 88, 89at 23 weeks, 88, 89at 27 weeks, 88, 90–91at 35 weeks, 88, 91at 41 weeks, 88, 92

Submucosa, 40Subserosa, 40Sulcal development, 287Syncytial knots. See Syncytiotrophoblastic knotsSyncytiotrophoblastic knots, 379

TTerminal villi, 379Tertiary follicles, 176

Testicular embryonic remnants, 140Testis

adrenal cortical rests, 139embryology

primordial germ cells, maturation process, 122seminiferous tubules, 121tunica albuginea, 122

embryonic remnants, 140histology

capsule layers, 123fetal Leydig cells maturation, 123fetal Leydig cells regression and dedifferentiation, 128germ cells maturation, 122, 127–128gonocytes fetal spermatogonia transformation, 10–13mini puberty, 135–136rete testis, 15 weeks gestation, 12420 to 40 weeks postmenstrual age, 128–13515 weeks gestation, 123–12517 weeks gestation, 125–12621 weeks gestation, 12923 weeks gestation, 129–13026 weeks gestation, 130, 13139 weeks gestation, 132, 13341 weeks gestation, 134, 13526 weeks gestation, rete testis, 131, 13239 weeks gestation, rete testis, 133–13441 weeks gestation, rete testis, 135

mesonephric remnantscystic, sessile appendix epididymis, 138embryonic rests, 139solid, pedunculated appendix epididymis, 138surface epithelium appendix epididymis, 139

paramesonephric remnants, 137Thalamus, 294, 297Thymic medulla, 248Thymus gland

architecture, 241–242capsule and connective tissue trabeculae, 242–243cortex

architecture and histological appearance, 244, 245extramedullary hematopoiesis, 247lymphocytes in, 244, 246–247staining of, 244, 246tingible body macrophages, 247

embryology, 241histology, 241–248medulla, 248stress involution of, 249–250thymic tissue, in ectopic sites, 249

Thyroid folliclescuboidal epithelial cells, 215at term, 221at 15 weeks gestation, 216at 18 weeks gestation, 217at 21 weeks gestation, 218at 26 weeks gestation, 219at 34 weeks gestation, 220

Thyroid glandembryology, 213

399Index

functional componentsparafollicular C cells, 221–222stroma, 222thyroid follicles, 215–221

histologyfetal neck organs, 214fetal/neonatal thyroid gland, 215

intrathryroidal inclusions, 223ultimobranchial body remnants, 223

Trilineage hematopoiesis, 276

UUltimobranchial body remnants, 223Umbilical cord

allantoic remnants, 369, 372arteries, 368, 370components of, 368vein and artery at term, 371vitelline duct remnant, 369, 371–372at 16 weeks gestation, 369, 370at 24 weeks gestation, 369at 35 weeks gestation, 370at 36 weeks gestation, 369Wharton’s jelly, 368, 369

Umbilical vein, 17Urinary bladder

adventitia, 118, 119bladder wall, 118embryology, 117–118histology, 118lamina propria, 118, 119muscularis propria, 119–120urothelium, 118, 119vesico-urethral canal, 117

Urogenital union, 144Urothelium, 118, 119Uterine cervix

at 23 weeks, 192at 24 weeks, 192at 32 weeks, 192, 193at 35 weeks, 193at 37 weeks, 193at 38 weeks, 193

Uterine corpus18 days after birth, 191endometrium

at 28 and 32 weeks, 190at 21 weeks, 190at 35 weeks, 191

eosinophilic cytoplasm, 191myometrium, 189, 190at 19 weeks, 188at 21 weeks, 189at 35 weeks, 191at 38 weeks, 191

Uterus

embryology, 187histology

uterine cervix, 192–193uterine corpus, 188–191

at 19 weeks, 188

VVagina

embryology, 195histology

at 18 days, postnatal life, 198at 23 weeks, 197at 25 weeks, 197at 32 weeks, 197, 198at 18 weeks gestation, 196

layers, 195Valve leaflets and cusps, fetal, 10–13Vascular tree, of spleen, 252Vas deferens

embryology, 153histology, 153–154

ampulla, 34 weeks gestation, 156at 17 and 20 weeks gestation, 154at 24 and 29 weeks gestation, 154at 34 weeks gestation, 155at 38 weeks gestation, 155

Verumontanum, 164Vesico-urethral canal, 117Villous parenchyma

chorionic villi, 381, 383–384by gestational age, 380mesenchymal villi, 378nucleated red blood cells, 379perivillous fibrin, 379placental tissue, at 6 weeks, 380–381placental villi, 381–385stem villi, 378syncytiotrophoblastic knots or syncytial knots, 379terminal villi, 379types and characteristics, 378, 379

Visceral pericardium. See EpicardiumVisceral pleura, 23

WWharton’s jelly, 368, 369White matter

cerebral cortex, 308–310myelination gliosis in, 288at term, 313, 314at 34 to 38 weeks, 308at 25 weeks, 300–301at 2 years postnatal, 316, 317

Woven bone, 331

YYolk sac remnant, 387