[HISTO] Female Repro

• menstrual cycle is the cyclical anatomical and physiological changes in the female reproductive system undergoes
• menstrual cycle ends permanently at menopause and temporarily during pregnancy
• primordial germ cells are the earliest recognizable stem cells of the female gamete
• PGCs emerge as epiblasts during the 2nd week of IUL
• epiblasts migrate to developing gonads while undergoing mitosis
• epiblasts reach developing ovaries at 5th week of IUL
• at developing ovaries, epiblasts differentiate into oogonia
• oogenesis is the term for the differentiation of oogonia to ova in the ovaries
• oogenesis starts at the end of 3rd month IUL and ends at 7th month IUL
• initial stage of oogenesis is the differentiation of oogonia into primary oocyte
• when oogenesis ends, all oogonia have fully differentiated into primary oocytes
• as soon as the primary oocyte forms, chromosomal replication starts via meiosis 1
• meiotic division of primary oocytes

  prophase 1 -> leptotene stage -> zygotene stage -> pachytene stage -> diplotene stage
• the "arrest" or "resting phase" is known as the dictyotene phase (lasts until puberty)
• the oocyte remains at "rest, "arrested", or in the dictyotene phase from before birth until around the time puberty commences
• primary oocytes are incapable of mitotic division, so its numbers will not replenish
• oogenesis


  stops at diplotene stage, daughter cells are not identical (3 polar bodies and 1 ovum),and daughter cells are not bound by cytoplasmic brifges
• spermatogenesis

  has no prolonged arrest phase, has identical and bounded daugher cells
• only one primary oocyte will be allowed to complete meiosis 1 per menstrual cycle
• the primary oocyte will complete meiosis 1 and produce 2 haploid daughter cells: secondary oocyte and first polar body
• secondary oocyte

  contains all the cytoplasm of the mother cell and starts meiosis 2 to form mature ovum (suspended at metaphase)
• first polar body


  contains minimal or completely lacks cytoplasm and is extruded due to incapability of further development
• no fertilization means that the mature ovum is degenerated
• fertilized mature ovum means that it has completed meiosis 2 and upon completion, a zygote and a second polar body are formed
• germinal epithelium is the lining epithelium of the human ovary
• germinal epithelium is composed of simple squamous to simple cuboidal epithelium
• tunica albuginea is a dense irregular connective tissue found directly under lining epithelium and forms an indistinct capsule
• the cortex is a thick peripheral zone found in the ovarian stroma that contains ovarian follicles supported by collagenous connective tissue
• the medulla is the vascular inner zone found in the ovarian stroma and is made up of loose connective tissue with a rich blood supply
• the ovarian follicles undergo structural and physiological changes during the menstrual cycles and is known as the ovarian cycle
• the follicular phase is governed by FSH, during the first 2 weeks of the ovarian cycle, and ends in ovulation
• the luteal phase is governed by LH, last 2 weeks of the ovarian cycle, and starts immediately after ovulation
• during ovulation, a follicle is released. this marks the end of the follicular phase and the start of the luteal phase
• the remnant of the ovarian follicle transforms into corpus luteum
• the primordial follicle consists of the following: primary oocyte and a single layer of flattened granulosa cells
• 3 types of ovarian follicle: primordial, primary, and secondary
• primary follicles are matured primordial follicles which consists of a primary oocyte and a stratified layer of cuboidal to columnar granular cell
• primary follicles also consists of a follicular fluid (liquor folliculi), zona pellucida, and theca folliculi
• before maturity into the primary follicle, the primordial follicular granular cells are in a single layer and are flattened
• upon maturity, the primary follicle consists of a stratified layer of cuboidal to columnar granular cells