M1: Parturition Phase I Flashcards
The average is cycle is ______ with a range of ________.
28 days. 25-32 days.
The development of predictable, regular, cyclical and spontaneous ovulatory menstrual cycle is regulated by the complex interactions of the
Hypothalamic-pituitary axis, Ovaries & Genital tract “HOG”
Released by the hypothalamus. Initiates the menstrual cycle. Transmitted from the hypothalamus to anterior pituitary gland. It signals the gland begin producing two hormones; ____ & ___.
GnRH. FSH & LH.
Active early in the cycle. Responsible for maturation of the ovum. Under the influence of this, the ovary begins to produce estrogen and the endometrium begins to proliferate.
FSH
A hormone that becomes most active at midpoint of the cycle. Responsible for ovulation or release of the mature egg cell from the ovary and growth of the uterine lining during the second half of the menstrual cycle. Aids in the formation of progesterone in the corpus luteum.
LH
Two members of the transforming growth factor-family. These two are triggers of the follicular development. FSH only enhances.
Growth differentiation factor 9 (GDF9) & Bone Morphogenetic protein 15 (BMP15)
Follicular development: FSH rise leading to follicle development is called
Selection window of the ovarian cycle
Follicular development: rise in parallel to growth of a dominant follicle and the increase in its number of granulosa cells (exclusive site of FSH receptor expression)
Estrogen
Small rise in the number signals ovulation. It maintains the pregnancy.
Progesterone
The increase in circulating ______ during the late luteal phase of the previous cycle stimulates an increase in FSH receptors and subsequently, the ability of ___________ to convert androstenedione to __________.
FSH. Cytochrome P450 aromatase. Estradiol.
The requirement of thecal cells which respond to LH & granulosa cells which responds to FSH, represents the ____________ for estrogen synthesis.
Two-gonadotropin, two-cell hypothesis
Conversion of androstenedione to estradiol
Theca cells
Progesterone positive feedback on pituitary leads to LH release. Inhibin negative feedback on pituitary to inhibit FSH.
Granulosa cells
The onset of the gonadotropin surge resulting from increasing estrogen secretion by preovulatory follicles is a relatively precise predictor of ovulation. It occurs ________ before the release of the ovum.
Ovulation. 34-36 hours.
Induces remodeling of the ECM to allow release of the mature oocyte with surrounding cumulus cells through the surface epithelium
LH
34-36hrs before release of the ovum from the follicle
Estrogen surge
Peaks at 10-12hrs before ovulation and stimulates the resumption of meiosis in the ovum with the release of the first polar body.
LH secretion
Post ovulation. Neovascularization. VEGF. Hypertrophy and increase capacity to synthesize hormones. Estrogen decreases with a secondary rise at the midluteal phase. Toward the end of this phase, there is secondary decrease in estradiol production.
Luteal or Postovulatory Phase
Granulosa lutein cells
Progesterone
________ develops from the remains of the dominant/graafian follicle in a process called _________. Rapidly regresses _______ days.
Corpus Luteum. Luteinization. 9-11.
Loss of luteal cells by apoptotic cell death. Decrease circulating estradiol and progesterone levels which are critical to allow the follicular develolment and ovulation during the next ovarian cycle.
Luteolysis
Correspond to follicular phase of the ovarian cycle. Increase estradiol. Re epitheliazation and angiogenesis. Glandular hyperplasia and increased stromal ground substance. Characterized by proliferation of vascular endothelial, stromal & glandular cells.
Proliferative/Preovulatory Endometrial Phase
Narrow & Tubular
Early proliferative
Endometrium thickens from bot glandular hyperplasia and increased stromal ground substance. Loss of stroma and the glands of the functionalis layer is widely spread.
Late proliferative
Determining the menstrual cycle day by endometrial histological criteria but is difficult during proliferative phase because of the considerable variation of phase length among women.
Dating
Correspond to luteal phase of the ovarian cycle. 12-14 days. Endometrial dating. Glandular epithelium histology. Window of implantation seem on days _______. Increase vascularization of spiral arteries.
Secretory or Postovulatory Endometrial Phase
Important in preparation of blastocyst implantation
Pinopodes
Between days _______ is striking changes associated with predecidual transformation of the 2/3 of the ________.
22-25. Functionalis layer.
Primarily secretes progesterone which is important to maintain pregnancy
Corpus Luteum
Life span of the egg
24hrs
Lifespan of the sperm
72hrs
Site of fertilization
Fallopian tube
Must be present in the fallopian tube at the time of the oocyte arrival
Spermatozoa
Still within the fallopian tube. Diploid 46 chromosomes. Surrounded by a thick zona pellucida. Forms the blastomeres, contain the polar body that are non functional and will soon regenerate.
Zygote(2/4/8 cell stage)
A solid mulberry like balls of cells. Enters the uterine cavity about 3 days after fertilization. Ends when the blastocyst forms.
Morula (16 cell stage