Definition:
The internal reproductive tract of primates is made up of the uterus, fallopian
tubes, ovaries, and vagina, and the supporting ligaments, blood vessels,
nerves, and lymph nodes related to these organs.
Structure:
The internal reproductive tract of primates is composed of a set of specialized
tubular organs formed from the Mullerian ductal system during embryogenesis,
plus the gonads. The fallopian tubes of
primates, called oviducts in lower mammals, retain their small (3-5mm)
diameter as bilateral structures connecting with the uterus. But the thick
uterus and thin-walled, distensible vagina
are formed as single, central organs by the coalescence of the lower portions
of the Mullerian ducts. The internal reproductive tract, has epithelial
linings of columnar, cuboidal, or squamous cells, and ends at distal vagina,
at the hymen, where the external reproductive
tract begins. These structures are the some of the target organs and
tissues for gonadal hormones. The supporting
ligaments, blood vessels, nerves,
and lymph nodes related to these organs
complete the tract.
Function:
The function of the internal reproductive tract has two parts: the preparation
of a dominant follicle and ovulation, and the retrieval of ova from the
pelvic cavity into the fallopian tube, and the nurture of the ovum
and sperm before fertilization, and the
embryo as it migrates into the uterus for implantation, growth and development.
Under the action of the ovarian hormones, estradiol from the follicles
and progesterone from the corpus luteum,
the endometrium undergoes a cyclic, repeated renewal and menstruation process
for supporting a conception. For oviparous mammals, the embryo implants,
develops a placental circulation in the endometrium where it grows and
develops into a mature fetus. At the end of the gestation period, the uterus
expels the fetus and placenta through the vagina and vestibule of the vulva.
