Histology: Gonads And Gametes Keywords

Front 1

Tunica Albuginea

Back 1

thick dense CT; appears white; capsule of the organ

Front 2

Mediastinium

Back 2

the thickened tunica albuginea located on the posterior portion of the testis

Front 3

Tunica Vaginalis

Back 3

surrounds the male testis; remnants of the peritoneal cavity

Front 4

Myoid cells

Back 4

fibroblast like cells that contain actin/myosin filaments (contractile)

Front 5

Seminiferous Tubules

Back 5

a web of loose CT that is rich in blood and lympathic vessesls, nerves, and Leydig cells. These tubules produce male reproductive cells, spermatozoa.

Front 6

Spermatogenesis

Back 6

Process by which spermatozoids are formed

1. Spermatogonium – primitive germ cell produces Type A Spermatogonia (stem cell) and Type B Spermatogonia

2. Type B spermatogonia – progenitor cells that differentiate into primary spermatocytes

3. Primary Spermatocyte – 1st meiotic division (22 day prophase); largest cells of spermatogenia; 46 chromosomes (44 + XY)

4. Secondary Spermatocyte – 2nd meiotic division; 23 chromosomes (22 + X/Y)

5. Spermatids- haploid cell; 23 chromosomes

6. Spermiogenesis: final stage, spermatids are transformed into spermatozoa (cell highly specialized to deliver male DNA to the ovum)
a. Formation of acrosome
b. Condensation & elongation of the nucleus
c. Development of flagellum
d. Loss of cytoplasm

Front 7

Acrosome

Back 7

spread over the condensed nucleus; contains several hydrolytic enzymes, such as hyaluronidase, neuroaminidase, acid phophatase and protease. This is a specialized type of lysosome. These enzymes are known to dissociate cells of the corona radiat and to digest the zona pellucida.

Front 8

Sperm Head

Back 8

contain the nucleus with condensed chromatin and the acrosome cap

Front 9

Sperm Middle piece

Back 9

contain mitochondria, axoneme, and dense fibers forming the thickened region.

Front 10

Sperm Principal piece

Back 10

constitutes most of the tail length; consists of a central core (axoneme)

Front 11

Sperm End piece

Back 11

contain axoneme only; very short tapering portion

Front 12

Sperm Dense fibers

Back 12

strengthening rods, sine wave like pattern

Front 13

Sperm Axoneme

Back 13

9 +2 arrangement of microtubules; generation of energy for flagellum.

Front 14

Sperm Residual bodies

Back 14

droplet of cytoplasm engulfed by Sertoli cells

-- Hormonal Influence
Testosterone – stimulates spermatogenesis
Estrogens & Progestogens – inhibit spermatogenesis
LH acts on interstitial cells (Leydig)
FSH acts on sertoli cells

-- Temperature important to production

Front 15

Sertoli cells

Back 15

elongated pyramidal supporting cells; rests on the basement membrane of the seminiferous tubule.
a. bound together by occluding juctions “blood-testis barrier”

b. Functions
- mediate all metablic exchange with the systemic compartment
- support, protection, and nutritional regulation of the developing spermatozoa
- Secretion – seminiferous tubule fluid
- Production of anti-mullerian hormone
- Blood-testis barrier
- Production of inhibin B
- phagocytosis of discarded spermatid cytoplasm

* stimulated by FSH from the adenohypophysis

Front 16

Testicular Fluid

Back 16

medium produced by the sertoli cells which contains steroids, proteins, ions, and androgen-binding proteins

Front 17

Leydig Cells

Back 17

principal cell type found in the interstitial supporting tissue between the seminiferous tubules; important site for the production of androgens.
- Synthesize and secrete male sex hormone Testosterone
- Stimulated by LH from the adenohypophysis

Front 18

Ovary Medullary region

Back 18

most internal part of the ovary; contains a rich vascular bed within a loose connective tissue

Front 19

Ovary Cortical region

Back 19

underneath the tunica albuginea it is the place where ovarian follicles dominate

Front 20

Ovary Germinal epithelium

Back 20

simple squamous or cuboidal epithelium

Front 21

Ovary Tunica Albuginea

Back 21

under the germinal epithelium a layer of dense connective tissue which is responsible for the whitish color of the ovary.

Front 22

Ovary Main functions

Back 22

- produce female gametes (oocytes)
- hold a fertilized oocyte during its complete development through embryonic and fetal stages until birth.
- produces secxual hormones that control organs of the reproductive system and influence other organs of the body

Front 23

Ovary Follicular Development

Back 23

1. Oogonia: during early fetal development these primordial germ cells migrate into the ovarian cortex where they multiply by mitosis.
2. Primary Oocytes: by the 4th or 5th month of hum fetal development some oogonia enlarge and assume the potential for development into mature gametes. Commence the 1st stage of meiosis
3. Primordial Follicles: a single layer of flattened cells surround the primary oocyte during the 7th month of fetal development. Meiosis remains at this stage (prophase) until the female reaches sexual maturity.
Note: all female germ cells are present at birth.

Front 24

Ovary Follicular Growth (types of follicles and details about each follicle type)

Back 24

1. Unilaminar primary follicle: FSH stimulates follicular growth causing the nucleus to enlarge and the number of mitochondria increases. Follicular cells divide by mitosis to form a single layer of cuboidal epithelium cells.
2. Multilaminar primary follicle: follicular cells form a stratified follicular epithelium (granulosa layer) whose cell communicate through gap junctions.
a. Zona Pellucida: a thick amorphous layer surrounds the oocyte and is secreted by several glycoproteins.
b. Granulosa layer (cells): stratified columnar epithelium; cell communicate through gap junction.
3. Secondary (antral) follicles: follicles grow and move deeper into the cortical region.
a. Cummulus Ooophrus: small hillock of cells that concentrate on the follicular wall layer and contains the oocyte.
b. Follicular fluid: a liquid that begins to accumulate between the follicular cells; hormones and signaling occurs here.
c. Antrum: a cavity small spaces of coalesced liquor fluid and surrounding granulose cells.
d. Theca interna: outer layer of the oocyte; produce the androstenedione steroid that is transported to the granulose layer.
e. Theca externa: consists mainly of organized layers of fibroblasts that surround the theca interna
4. Graafian, Mature (preovulatory) follicle: the dominant follicle of a group of growing follicles enters the most developed stages of follicular growth and undergo

Front 25

Ovulation

Back 25

consists of the rupture of part of the wall of the mature follicle and liberation of the oocyte. Takes place around the 14 day of the menstrual cycle.

- LH: stimulates ovulation; in response to high circulating estrogen levels. Occurs within minutes after the increase in blood LH.
- 1st meiotic division is completed just before ovulation (until this moment the oocyte was in prophase I of meiosis)

Front 26

Corpus Luteum

Back 26

temporay endocrine gland containing the granulose cells and the cells of the theca interna of the ovulated follicle.
- Granulosa lutein cells: steroid secreting cells
- Rich vacular system develops in the interior
- Begin to secrete progesterone and estrogens
- Mensturation: caused by the decrease in progesterone
- Pregnancy occurs – corpus luteum secretes human chorionic gonadotropin (HCG)

Front 27

Theca Lutein cells

Back 27

secrete estrogen which are necessary to maintain the thickened uterine mucosa

Front 28

Granulosa lutein cells

Back 28

under the influence of LH granulose cells increase greatly in size and begin secretion of progesterone.

Front 29

Corpus Albicans

Back 29

“white bodies” a scar of dense connective tissue (collagen) produced by fibroblasts invading the area. Corpus albican represents the fate of the corpus luteum after pregnancy does not occur. It causes by the decrease of progesterone secretion.

Front 30

Ovary Interstitial cells

Back 30

active steroid secretors stimulated by LH; remenants of theca interna cells after atresia.

Front 31

Atresia

Back 31

the degeneration of female germ cells at any stage of follicular maturation. The oocytes are disposed by phagocytic cells.

Front 32

Endocrine functions of corpus luteum and follice

Back 32

Corpus luteum: after ovulation the granulose cells and cells of the theca interna of the ovulated follicle reorganize to form a temporary endocrine gland, which is embedded with the cortical region. Secrete progesterone and estrogen.

Follicle: The theca interna secrete progesterone and estrogen precursors. They promote proliferation of the endometrium in readiness for the implantation of a fertilized ovum.