In the streptozocin-induced diabetic rat, the placenta is larger and the fetus is smaller than normal. To study cellular differences that might contribute to the size and functional disparity between diabetic and control placentas, a light- and electron-microscopic analysis was performed on 14-, 18-, and 22-day (term) control and diabetic placentas. Diabetic placentas, especially later in gestation, were marked by the presence of large numbers of glycogen-distended cells in the basal zone. Within the placental labyrinth, the trophoblastic layers of the interhemal membrane were significantly thicker in the diabetic placentas on days 18 and 22, and large accumulations of liid droplets were present, especially in the inner two trophoblastic layers. In normal placentas there is a marked thinning of the placental barrier in the labyrinth by day 22 of gestation, making the thickness of the labyrinthine layers in age-matched diabetic placentas even more impressive. Finally, the labyrinth of 22-day diabetic placentas contained more glycogen and rough endoplasmic reticulum in the inner trophoblastic layer, a feature that is found in less-mature (18-day) control placentas. Thus, the diabetic placentas have a number of features that are consistent with functional immaturity/dysmaturity. Cytologic evidence confirms the presence of increased glycogen and lipid reserves in both the junctional zone and the cellular area between maternal and fetal blood.(ABSTRACT TRUNCATED AT 250 WORDS)
The cardio-respiratory response to hypoxia is the subject of intense research in human infants •, but is mostly limited to noninvasive studies. Animal investigation is an attractive alternative, but most animal studies have involved anesthetized or nonintact preparations , which may not reflect human physiology. The cardio-respiratory responses to hypoxia are not well documented in unanesthetized intact newborn animals. In particular, there is little information on the periodic breathing (PB) response to hypoxia and, hence, on the practicality of an animal model for PB.. We studied heart rate (HR) and respiratory responses during quiet sleep to 17% Flo 2 in unanesthetized full-term newborns o f five species; lamb, piglet, puppy, kitten, and rabbit (N=31). ECG, HR and respirogram monitoring was used. There was no significant change in mean HR and respiratory rate (RR) with hypoxia for any species. Brief apneas > 5 sec. were both in 21% and 17% o 2 , but only in lambs and puppies. No sustained periodic breathing was induced by hypoxia; although in three speCies, there was one brief episode. We conclude that mild hypoxia has little effect on HR and RR in these unanesthetized newborns. Respiratory patterns showed some apneas in only two species, but these were not significantly affected by hypoxia. Periodic breathing was not frequent enough to make an animal model practicable. This may indicate considerable maturit y of respiratory contro l in full-term newborns of these species.
The cardio-respiratory response to hypoxia is the subject of intense research in human infants, but is mostly limited to noninvasive studies. Animal investigation is an attractive alternative, but most animal studies have involved anesthetized or nonintact preparations, which may not reflect human physiology. The cardio-respiratory responses to hypoxia are not well documented in unanesthetized intact newborn animals. In particular, there is little information on the periodic breathing (PB) response to hypoxia and, hence, on the practicality of an animal model for PB.-We studied heart rate (HR) and respiratory responses during quiet sleep to 17% Fl0 2 in unanesthetized full-term newborns of five species; lamb, piglet, puppy, kitten, and rabbit (N=31). ECG, HR and respirogram monitoring was used. There was no significant change in mean HR and respiratory rate (RR) with hypoxia for any species. Brief apneas > 5 sec. were
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