Uanatomy of M + F Repro : Bendiak Flashcards
Where does meiosis take place during the development of spermatozoa from spermatogonia?
Seminiferous tubules
Fxn of rete testes
region of anastomosing channels where the nonmotile spermatozoa enter and be moved to efferent ductules –> epididymus
- makes sense that it contains connective tissue with myoid cells: can contract and move sperm
How do the efferent ductules move the still immotile sperm?
They are lined by a mixture of columnar ciliated cells
(and cuboidal absorptive cells)
Each ductulus also has a band of circularly arranged SM around it to facilitate spermatozoa propulsion into the epididymus
Why are the ductuli (efferent ductules) and epididymus so structurally different?
Ductuli arise embryonically from primitive tubules that comprise the mesonephros
Epididymus arise from mesonephric (Wolffian) duct itself.
When does the vas deferens become the ejaculatory duct?
when the vas deferens meets the seminal vesicle
How do the seminiferous tubules help to propel the developing spermatozoa?
They have an outer basal lamina surrounded by myofibroblasts
- contract + propel spermatozoa
Spermatogenesis initially occurs with _____.
- What is it?
- What does it become once committed?
- Where is it found?
mitotic division of type A spermatogonia (2N)
- true stem cells that divide to totipotent progenitors
- once committed to meiosis, become type B spermatogonia
*found in outer region of tubules
How many chromosomes do primary spermatocytes have? (they form from type B spermatogonia)
4 C (chromosomes)
during cross over events during meiosis
- develop as primary spermatocyte at 3 weeks, then undergo meiosis II as secondary spermatocytes
How long do primary, secondary spermatocytes develop for?
Primary: 3 weeks
Secondary: 2 hours
hardly ever observed
- quickly progress to spermatids
What is special about the entire process of meiosis (in sperm development)?
during the entire process of meiosis, the cells derived from a given spermatogonium remain linked as a syncytium with a connected cytoplasmic bridge.
- Important for RNA exchange between developing haploid spermatids
(many recessive genes being exchanged)
During spermatogenesis, the interconnected cells (during meiosis) that are underdeveloped are surrounded by ____.
sertoli cells
blood testes barrier
Comprise of Sertoli cells via tight jxns.
- seal off spermatocytes
*spermatogonia at the base of the seminiferous epithelium are not contained in the barrier
What secretes androgen binding protein? What is its fxn?
Sertoli cells
- ABP binds T and sequesters high levels of testosterone (200x as [ ] as the blood)
*sertoli cells also produce inhibin that feeds back to the hypothalamus to inhibit FSH
When do spermatozoa gain motility?
En route along the epididymus
they are not motile when leaving the testes
OOcytes are derived from a population of ____.
primordial follicles
primordial germ cells divide mitotically up to 5 months gestation –> stop in meiosis I
What is the ovarian surface covered by?
Single layer of epithelial cells: germinal epithelium
What surrounds oocytes in the ovary during development?
Primordial follicle
–> become cuboidal = primary follicles
–> acquire more than 1 layer = granulosa cells
- multiple layers of granulosa cells surround large primary/secondary follicle
- theca cells surround granulosa cells
When are primary/secondary follicles stimulated to develop into large Graafian follicles (antral follicles) having fluid filled antrum?
After menarche
- granulosa cells proliferate and thecal cells enlarge –> graafian follicle
- remember the oocytes remain in prophase I around 6 mo after birth.
- also remember, the atretic follicles that form form primary follicles when Graafian (antral) follicles do not form
Atretic follicles
the left over primary follicles that do not develop to antral (Graafian) follicles
Thecal cells produce ____, which is converted to _____ by granulosa cells.
androstenedione
estradiol
Corpus luteum
large endocrine group of cells that were remodeled from remaining granulosa and thecal cells after an OVULATORY FOLLICLE successfully releases an OOCYTE
*this occurs monthly and is driven by LH production
What controls the release of the corpus luteum?
LH production around 12 days into the cycle and is referred to as luteinization
Corpus albicans
corpus luteum degenerates into corpus albicans
- a residual body if implantation does not occur
2 fates of the corpus luteum
- No fertilization
- -> degenerates into corpus albicans - Fertilization/implantation –> Corpus luteum enlarges under the influence of chorionic gonadotropin –> responsible for maintenance of pregnancy
* placenta and CL are responsible for maintenance of pregnancy
