Blastocyst

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physicians calculate the age of the embryo or fetus from the 1st day of the last normal menstrual period

(approx 2 weeks longer than fertilization age)

a secondary oocyte that has been impregnated by a sperm

(is a zygote when fertilization is complete)

• cranial (head, superior)
• caudal (tail, inferior)
• ventral (anterior)
• dorsal (posterior)

uterus

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thick-walled, pear-shaped female reproductive organ; 2 main parts:

body-expanded superior 2/3

cervix-cylindrical inferior 1/3

walls of the body of uterus (3 layers)

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• perimetrium: thin external layer of peritoneum
• myometrium: thick smooth muscle layer
• endometrium: thin internal mucous membrane

a constricted opening of the cervical canal (lumen of cervix)

• internal os: communicates with the cavity of the body of the uterus
• external os: communicates with vagina

          endometrium

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internal layer of uterus; at peak of development is 4 to 5 mm thick; during luteal (secretory) phase of menstrual cycle 3 layers visible microscopically:

• compact layer: densely packed connective tissue around neck of uterine glands
• spongy layer: edematous connective tissue containing dilated, tortuous bodies of uterine glands

*compact and spongy layers r collectively the functional layer; disintegrate and r shed at menstruation & parturition (delivery of infant

• basal layer: containing the blind ends of uterine glands; has own blood supply and not cast off during menstruation

measures 10 cm long and 1 cm diameter; extend laterally from horns; divided into 4 parts:

• infundibulum
• ampulla (fertilization site)
• isthmus
• uterine part

*tubes carry oocytes from ovaries and sperms entering cervix to reach fertilization site in the ampulla of the uterine tube. The uterine tubes then conveys the dividing zygote to uterine cavity

almond-shaped glands located on each side of uterus that produce oocytes; produce estrogen and progesterone (hormones responsible for development of secondary sex characteristics and regulation of pregnancy)

• vagina
• uterus
• uterine tubes
• ovaries

known collectively as the vulva:

• labia majora: fatty external folds of skin, conceal vaginal orifice (opening of vagina)
• labia minora: inside labia majora; 2 smaller folds of mucous membrane
• clitoris: erectile organ; situated at superior junction of folds
• the vagina and urethra open into cavity, vestibule (cleft between labia minora)
• hymen: fold of mucous membrane that surrounds vaginal orifice

• penis
• testes
• epididymis
• ductus (vas) deferens
• prostate
• seminal glands
• bulbourethral glands
• ejaculatory ducts
• urethra

formation of germ cells through a process which prepares these sex cells for thier role in fertilization (meiosis which occurs during gametogenesis reduces the # of chromosomes to 23):

• in males process is spermatogenesis
• in females process is oogenesis

• primordial sperms --spermatogonia (46, diploid) -- are transformed into mature germ cells (sperm)
• begins at puberty
• before maturation, these sperm remain dormant in seminiferous tubules of testes from fetal period - puberty at which they increase in bumber

• spermatagonia grow and transform into primary spermatocytes;
• the largest germ cells in the seminiferous tubules
• will undergo 1st meiotic division (reduction division) to form 2 haploid secondary spermatocytes

• resulting from 1st meiotic division of primary spermatocytes; 
• approximately 1/2 the size and (23, haploid)
• undergo 2nd meiotic division to form 4 haploid spermatids (1/2 size)

• 1/2 the size of secondary spermatocytes
• gradually transformed into 4 mature sperms during process called spermiogenesis

• metamorphosis (change in form)
• nucleus condenses
• acrosome forms
• most cytoplasm is shed
• when complete, sperm enter the lumina of seminiferous tubules, then move to epididymis, where they r stored and becom functionally mature

• free-swimming, actively motile cell
• consisting of a head (bulk of sperm containing nucleus)
• head is covered by acrosome
• consists of a tail for motility (3 parts: middle, principal & end pieces)
• middle piece has mitochondria
• a neck seperates the head and tail