Structure and permeability of the egg capsule of the placental Australian sharpnose shark, Rhizoprionodon taylori.
J Comp Physiol B
; 192(2): 263-273, 2022 03.
Article
en En
| MEDLINE
| ID: mdl-35118516
ABSTRACT
Shark placentae are derived from modifications to the fetal yolk sac and the maternal uterine mucosa. In almost all placental sharks, embryonic development occurs in an egg capsule that remains intact for the entire pregnancy, separating the fetal tissues from the maternal tissues at the placental interface. Here, we investigate the structure and permeability of the egg capsules that surround developing embryos of the placental Australian sharpnose shark (Rhizoprionodon taylori) during late pregnancy. The egg capsule is an acellular fibrous structure that is 0.42 ± 0.04 µm thick at the placental interface between the yolk sac and uterine tissues, and 0.67 ± 0.08 µm thick in the paraplacental regions. This is the thinnest egg capsule of any placental shark measured so far, which may increase the diffusion rate of respiratory gases, fetal wastes, water and nutrients between maternal and fetal tissues. Molecules smaller than or equal to ~ 1000 Da can diffuse through the egg capsule, but larger proteins (~ 3000-26,000 Da) cannot. Similar permeability characteristics between the egg capsule of R. taylori and other placental sharks suggest that molecular size is an important determinant of the molecules that can be exchanged between the mother and her embryos during pregnancy.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Tiburones
Límite:
Animals
/
Pregnancy
País/Región como asunto:
Oceania
Idioma:
En
Revista:
J Comp Physiol B
Asunto de la revista:
BIOQUIMICA
/
FISIOLOGIA
/
METABOLISMO
Año:
2022
Tipo del documento:
Article
País de afiliación:
Australia