HCG Differentiation | Lecture Note

University:
The University Of Western Ontario
Course:
ANAT 2200B | Systemic Anatomy of the Human Body
Academic year:

2022
Views:

485

Pages:

3
Author:

Kyuwon J.

hCG structures ● Heterodimeric glycoprotein hormone ○ a-subunites ■ LH ■ FSH ■ TSH ○ B-subunits ■ biological specificity ● Disfunded bonds ○ S-S ■ stabilization of both subunits ● N-linked glycans ○ both a and B ● O-linked glycans ○ predominant B-subunits ● glycosylation affects ○ hormonal stability ○ circulating half life ○ receptor binding ● B-subunit is portion where clinical assay will target Morphological Differentiation ● Villous cytrophoblasts ○ VCT ■ Mononuclear ■ proliferative cells ○ Over 24-72 hours ■ aggregate ■ Fuse ■ Differentiation into syncytiotrophoblasts ● ST ● significance ○ syncyotiotrophoblast is multinucleated ■ non-proliferative ■ primary endocrine unit ● Placenta ○ hCG synthesis will increase once the cell fuses into ST Functional Differentiations ● Cell fusions to hormonal outputs ○ ~24h ■ low secretion ● free hCG a ● free hCG B ■ small action of intact hCG ○ ~72h ■ syncytialization ● marked to increase in intact hCG ● Increase in synthesis of B-subunits ● a+B assembly now efficient ● formation of syncytiotrophoblast needs coordination of hCG secretions ○ hCG is used as indicators for placental functional maturity ○ poor syncytialization ⇒ abnormal hCG levels Secretion patterns (maternal blood) ● Normal pregnancy patterns ○ intact hCG ○ peak in 9-10w ○ declines after then plateaus ● free hCG a ⇒ increases ● free hCG B ⇒ low relativity ot intact hCG Interpretation ● Intact hCG circulateing hormones ○ trophoblastic turnover ○ differentiation ○ Placental path Interpretations (high yeild) ● hCG structures ○ relient on proper subunit assembly + glycosylations ● Morphological differentiation ○ VCT⇒ST ○ Promotes endocrine functions ● Functional differentiation ○ increase in intact hCG secretion ● Serum hCG patterns ○ placental development ○ health