Week 6: Repro Histology Flashcards
tunica albuginea
tough CT covering over each testis
lobules of testis
- fibrous sept divide it into 250-300 lobules
* each lobule has 1-4 seminiferous tubules
rete testis
•network of channels that collects products of seminiferous epithelium
seminiferous tubules produce
sperm, secretory proteins, and ions
space between seminiferous tubules filled with
abundant blood vessels and aggregates of andogen producing Leydig cells
Leydig cells respond to ___ and produce___
LH; testosterone
2 distinct cell populations in seminiferous epithelium
- somatic Sertoli cells
2. spermatogenic cells
Sertoli cells
- columnar epithelium containing light staining nutrients with a prominent nucleus
- connected by tight junctions to form basal and adluminal compartment within the tubule
“blood-testis barrier”
- tight junctions between Sertoli cells are components
* protects developing spermatogenic cells within adluminal compartment from autoimmune reactions
other functions of sertoli cells
- phagocytose residual germ cell cytoplasm
- regulate release of mature spermatozoa
- secrete andogen binding protein (ABP) in response to FSH stimulation
Andogen binding protein (ABP)
functions to concentrate testosterone produced by the leydig cells in the seminiferous tubules to stimulate spermatogenesis
Spermatogenic cells include
spermatogonia, spermatocytes, and spermatids
spermatagonia
- diploid stem cells of the testis
- small dense oval nuclei and are closely associated with seminiferous tubular wall
- divide by mitosis to generate 2 daughter cells
spermatogonia that enter the spermatogenesis cell sequence
divide and give rise to primary speramtocytes (also diploid)
secondary spermatocytes
•haploid cells
•primary spermatocytes enter meiosis I to give rise to these
they differentiate into haploid spermatids during meiosis II
primary and secondary spermatocytes in H and E sections
- indistinguishable from one another
- will be located far from tubular wall within adluminal compartment
- have large nuclei containing dark-staining chromatin
spermatids in H and E sections
- even closer to the lumen of the tubule
* identified by small dense dark staining nuclei that dan appear round in early spermatids and oblong in late spermatids
spermatogenesis
- process of sperm cell development
* seminiferous epithelial cells undergo successive mitotic and meiotic divisions to produce spermatozoa
spermiogenesis
- last step of spermatogenesis
* spermatids undergo dramatic change in form to become the streamline spermatozoa adapted for fertilization
changes to spermatids in spermiogenesis
- nuclear condensation
- formation of acrosomal cap
- development of tail
sperm are nonmotile until
they mature in the epididymis where they acquire forward motility
epididymis consists of
- highly elongated coiled tubules where sperm mature and are stored
- classically divided into head, body, and tail
epithelium of epididymis
•pseudostratified columnar with long and branched stereocilia
•two major cell types:
1. columnar principle cells from lumen to basal lamina; their apical domain display branched stereocilia
2. basal cells associated with basal lamina regarded as the precursors of the principle cells (stem cells)
smooth muscle of epididymis
- head surrounded by smooth circular muscle
* body and tail have an increased thickness of smooth circular plus an outer longitudinal smooth muscle layer
vas deferens
- continuous with epididymis
- lined by pseudostratified columnar with stereocilia and supported by CT lamina propria with elastic fibers
- muscular wall has inner and outer longitudinal muscle separated by a middle circular layer
- external layer has loose CT and adipose cells
ampulla of vas deferens
leads directly into the prostate gland and fused with the duct of the seminal vesicle, forming the ejaculatory ducts that empty into the prostatic urethra
prostate
- largest accessory reproductive gland
* 30-50 branched tubuloalveolar glands that empty contents into prostatic urethra
glands of prostate are surrounded by smooth muscle cells and CT and are arranged into 3 specific zones
- transition zone closes to and surrounding the prostatic urethra
- central zone
- a peripheral zone
prostate glands are lined with
- combination of simple and pseudostratified columnar epithelium
- lumen of glands often contain concretions (corpora amylacea) rich in glycoproteins that are sometimes a site of calcium deposition
glands of prostate produce
zinc-rich alkaline fluid that neutralizes the acidity of the vagina, provides nutrients, transports sperm, and liquefies semen
benign prostate hyperplasia (BPH)
- condition that occurs with aging
- enlargement of prostate that can restrict flow of urine through prostatic urethra
- the cells and stroma of the periurethral central and transitional zones are involved
prostate cancer
- originates from the main prostate glands of the peripheral zone, farthest from the urethra
- urinary symptoms are not present at the early stage and tumor growth often detected by digital palpation of prostate, elevated serum levels of prostate specific antigen (PSA), or by back pain caused by vertebral mets
2 coexisitng events during menstrual cycle
ovarian cycle and uterine cycle
ovarian cycle
several ovarian follicles, each housing a primary oocyte undergo a differentiation process (golliculogenesis) in preparation for ovulation into oviducts or fallopian tubes
uterine cycle
- endometrium is preparing for embryo implantation
- if fertilization of ovulated egg does not take place, endometrium is shed, menstruation occurs, and a new menstrual cycle begins
ovaries
- lined with simple squamous to low cuboidal epithelium
- subjacent CT layer called tunic albuginea
- cortex and medulla w/o distinct demarcation can be visualized in cross section
cortex of ovary
contains CT and primordial follicles housing primary oocytes (arrested in prophase of meiosis I
medulla of ovary
consists of CT, interstitial cells, nerves, lymphatics, and blood vessels reaching the ovary through the hilum
surface epithelium cells of ovary important function
- repair damage caused to ovary after each ovulation
- cells with this characteristic stem cell phenotype can also be found in the fimbria of the oviduct
- They are postulated to be the origin of some ovarian carcinomas
3 phases of ovarian cycle
follicular phase (folliculogenesis), ovulatory phase, and luteal phase
ovarian cycle controlled by
secretion of hormones FSH (follicle stimulating hormone) and LH (luteinizing hormone) and results in production of estrogen and progesterone
follicular phase
- sequential development of several primordial follicles
- generally only one completes development, and the others degenerate through apoptotic process called atresia
- atresia ensures that only viable follicles, containing oocytes with optimal quality for fertilization are available throughout the reproductive period
atretic follicles
a large number of atretic follicles retain hormonal activity thereby contributing to the endocrine function of the ovary that prepares the endometrium for implantation
primordial follicles
contains the diploid primary oocyte arrested in prophase of meiosis I
initiation of folliculogenesis
•in response to FSH, several primordial follicles, each surrounded by simple squamous granulosa cells, initiate folliculogenesis
primordial follicles become primary (unilayered) follicles when
the single layer of squamous granulosa becomes a simple cuboidal granulosa layer
granulosa cells secrete ___ in response to ___
estrogen; FSH
zona pellucida
gradually assembles to separate the primary oocyte from the granulosa cells
secondary (multilayered) follicles
- they become secondary follicles when the granulosa cells proliferate into stratified cuboidal epithelium and continue secreting estrogen
- a cellular shell, or theca, surround the follicle
theca
- begins to organize into 2 layers in the stage of secondary follicle
- theca interna - vascularized cell layer adjacent to the basal lamina supporting the granulosa
- theca externa - fibrous cellular layer continuous with ovarian stroma
antral follicle
- small intercellular spaces develop in the granulosa, they contain follicular fluid
- spaces usually coalesce into a single space called the antrum
preovulatory follicle (graffian)
•antrum reaches its max size and the fluid of the antrum segregates the granulosa cells into 3 regions:
- cumulus oophorous, anchoring the oocyte to the wall of the follicle
- granulosa cells lining wall of follicle
- layer of granulosa cells anchored to zona pellucida by processes called corona radiata
ovulatory phase
•marture follicle protrudes from ovarian surface
•surge of LH causes graffian follicle to rupture
•released gamete enters the uterine tube or oviduct as it completes meiosis I and produces first polar body
•Oocyte it now haploid secondary oocyte that is arrested in metaphase of meiosis II
It completes meiosis II and releases a second polar body
Luteal phase
- after ovulation, residual granulosa cell layer folds and becomes part of the corpus luteum, a major hormone secreting gland
- granulosa become granulosa lutein cellsthat secrete progesterone and estrogen in response to LH and FSH
- theca externa cells become theca lutein which produce androstenedion and progesterone in response to LH
- within the granulosa lutein cells, the androstenedion is converted to estradiol by aromatase
regression of corpus luteum
- luteolysis
* leads to formation of corpus albicans from CT replacing the mass of degenerating luteal cells of the corpus luteum
wall of the body of the uterus consist of
endometrium, myometrium, adventitia/serosa
myomtrium
3 poorly defined smooth muscle layers. Central layers is thick with circularly arranged fibers and abundant blood vessels. The inner and outer layers have longitudinally or obliquely arranged fibers
what happens to myometrial layers during pregnancy?
they hypertrophy and fibers increase in number (hyperplasia)
endometrium consists of
simple columnar epithelial lining with simple tubular endometrial glands and lamina propria, called endometrial stroma
2 layers of endometrium
- superficial functional layer - lost during menstruation
* basal layer - retained as the source of regeneration of a new functional layer following menstruation
4 phases of menstrual cycle
menstrual, proliferative, secretory, ischemic
menstrual phase
- 4-5 days
* initial phase of the cycle
proliferative phase
- about 9 days
- also called estrogenic or follicular phase
- thickness of endometrium (about .5-1 mm) increases due to estrogen produced by maturing ovarian follicles
day 14 in menstural cycles
ovulation occurs
secretory phase
- begins after ovulation
- about 13 days long
- also called progestational phase
- endometrium is now about 5-7 mm thick and endometrial glands begin their secretory activity
- This phase controlled by progesterone and estrogen produced in corpus luteum
ischemic phase
- about 1 day long
- regression of corpus luteum leads to a reduction in normal blood supply, causing intermittent ischemia and hypoxia, induces necrosis of functional layer of endometrium
endocervix
- lined by folded mucosa with deep crypts, mimicking a system of mucus-secreting tubular glands
- mucus producing cells are simple columnar and their height varies with time of menstrual cycle
secretory activity of endocervix
- regulated by estrogens and is maximal at the time of ovulation
- the secreted mucous lubricates the vagina, acts as antibacterial protective barrier, and creates favorable conditions for sperm migration
ectocervix
•lined by stratified squamous epithelium
tranformation zone
abrupt epithelial transition between endo- and ectocervix
dysplasia at the transformational zone
- disorganized epithelial cells that slough off before reaching full stratified maturity
- abnormal, but reversible
- can lead to carcinoma in situ
3 layers of the vagina
inner mucosal, middle muscularis, outer adventitial
inner mucosal layer of vagina consists of
stratified squamous with lamina propria usually infiltrated by neutrophils and lymphocytes
oviduct
site of fertilization and early cleavage of zygote
4 regions of oviduct
- proximal fimbriated infundibulum
- long and thin walled ampula
- short and thick walled isthmus
- intramural portion opening into lumen of uterine cavity
3 layers of oviduct wall
- mucosa supported by lamina propria
- muscularis
- serosa
mucosa of oviduct
simple columnar with 2 cell populations under hormonal control: ciliated cells and nonciliated secretory cells (peg cells)
cilated cells of oviduct mucosa
- enlarge and produce cilia as folliculogenesis and estrogen production is in progress
- estrogens increase rate of ciliary beat
- during luteolysis, cilia are lost
Peg cells of oviduct mucosa
secretory activity stimulated by estrogens
