HISTOLOGY REVIEWHISTOLOGY REVIEWReproductive SystemReproductive System

Dr. Tim BallardDr. Tim Ballard

Department of Biology and Marine BiologyDepartment of Biology and Marine Biology

Each testis contains 250 – 900 seminiferous tubules that are responsible for the production of spermatozoa and testosterone.

Male Reproduction -- TestisMale Reproduction -- Testis

Seminiferous tubule– cross section – H&E – 10x objective

lumen

Each seminiferous tubule is formed of an epithelium resting on a basement membrane. The cell types seen are in various stages of meiosis.

Male Reproduction -- TestisMale Reproduction -- Testis

Seminiferous tubule– cross section – H&E – 10x objective

lumen

basement membrane

nests of interstitial cells (of Leydig) in connective tissue

surrounding tubules

Spermatogonia (2n2c) lie on the basement membrane and are mitotic. Some respond to FSH and enter meiosis, moving off the basement membrane and towards the lumen.

Male Reproduction -- TestisMale Reproduction -- Testis

Seminiferous tubule– cross section – H&E – 10x objective

lumen

basement membrane

spermatogonium

spermatogonium

spermatogonium

2º spermatocytes and spermatids cannot be distinguished morphologically.

Male Reproduction -- TestisMale Reproduction -- Testis

Seminiferous tubule– cross section – H&E – 40x objective

spermatogonia (2n2c)

1º spermatocytes (2n4c)

2º spermatocytes (1n2c)

spermatids (1n1c)

spermatozoa (1n1c)

lumen

sustentacular (Sertoli) cell

Spermatogenesis is the process of meiosis in the male wherein one spermatogonium becomes 4 spermatids. The spermatids then enter spermiogenesis, associated with the Sertoli, and transform anatomically into anatomically mature spermatozoa.

The erectile tissues consist of lacunae, spaces that fill with blood, surrounded by collagenous connective tissue (the tunica albuginea).

Male Reproduction -- PenisMale Reproduction -- Penis

Primate penis– cross section – H&E – 4x objective

tunica albuginea

corpus cavernosum

corpus cavernosum

corpus spongiosum

urethra

deep artery

deep artery

dorsal vein

Review the basic structure of the ovary and the stages of follicular development before looking at the slides.

Female Reproduction -- OvaryFemale Reproduction -- Ovary

primordial follicles

primary follicles

secondary follicle

tertiary follicle

corpus luteum

corpus albicans

ovulation

medulla

cortex

Primordial follicles are quiescent structures, awaiting stimulation from FSH before reentering their developmental pathway.

Female Reproduction -- FolliclesFemale Reproduction -- Follicles

Mammalian ovary– section – H&E – 4x objective

Look along the periphery of the ovary for clusters of primordial follicles. Each consists of a primary oöcyte (2n4c) surrounded by a single layer of flattened follicle cells.

primordial follicles

Once stimulated, by FSH, 30-50 primordial follicles reenter development, and become primary follicles.

Female Reproduction -- FolliclesFemale Reproduction -- Follicles

Mammalian ovary– section – H&E – 4x objective

Several events occur here. Follicle cells become cuboidal, begin mitosis, and begin to secrete estrogen. The primary oöcyte becomes unarrested from prophase I and begins its first meiotic division.

primary multilaminar follicle

primary oöcytefollicle

cells

Female Reproduction -- FolliclesFemale Reproduction -- Follicles

Mammalian ovary– section – H&E – 10x objective

As it matures, the primary multilaminar follicle has 5-7 layers of follicle cells and develops a glycoprotein coat just outside the cell membrane of the oöcyte called the zona pellucida.

zona pellucida

At this stage the developing ovum is likely to be a secondary oöcyte (1n2c) now, having finished its first meiotic division. It now becomes arrested at metaphase II.

The last stage, the tertiary follicle, has the same basic structure as above, just larger with the ovum more eccentric.

Female Reproduction -- FolliclesFemale Reproduction -- Follicles

Mammalian ovary– section – H&E – 4x objective

secondary oöcyte

The follicle becomes a secondary follicle when there is a clearly discernable antrum or cavity within the follicle. As the follicle continues to get larger, the antrum enlarges and the ovum becomes more eccentric (off center).

zona pellucida

antrum

cumulus oophorus

stratum granulosum

When you start this slide, scroll through the whole thickness and identify where the endometrium with its glands stops and the myometrium begins.

Female Reproduction -- UterusFemale Reproduction -- Uterus

Mammalian proliferative uterus– section – H&E – 10x obj.

In the proliferative stage of the uterine cycle, under control of rising estrogen from the developing follicles, the stratum basalis is regrowing the stratum functionalis, which was shed during the previous menstrual flow. The diagnostic feature of this stage are the long and straight uterine glands which are not yet functional.

uterine glands

When you start this slide, scroll through the whole thickness and identify where the endometrium with its glands stops and the myometrium begins.

Female Reproduction -- UterusFemale Reproduction -- Uterus

Mammalian secretory uterus– section – H&E – 40x objective

In the secretory stage of the uterine cycle, under the control of estrogen and progesterone from the corpus luteum, the uterine glands of the stratum functionalis begin to be functional, producing glycogen. The diagnostic feature of this stage are the curvy, serrated-looking glands.

uterine glands

When you start this slide, scroll through the whole thickness and identify where the endometrium with its glands stops and the myometrium begins.

Female Reproduction -- UterusFemale Reproduction -- Uterus

Mammalian menstrual uterus– section – H&E – 4x objective

In the menstrual stage of the uterine cycle, under the control of lack of estrogen and progesterone from the dead corpus luteum, the stratum functionalis dies and loses its anatomical integrity, breaking lose and shedding from the stratum basalis.

uterine cavity myometriu

m

shedding stratum functionalis

When you start this slide, scroll through the whole thickness and identify where the endometrium with its glands stops and the myometrium begins.

Female Reproduction -- UterusFemale Reproduction -- Uterus

Mammalian menstrual uterus– section – H&E – 4x objective

Compare the anatomical integrity of this endometrium with the previous slides of proliferative and secretory uterus. This is a mess as it comes completely undone.

uterine cavity myometriu

m

shedding stratum functionalis