II.—Cyclic Variations in the Vascular Architecture of the Uterus of the Guinea Pig

Bacsich, Paul; Wyburn, G. M.

doi:10.1017/s0080456800017828

Cited by 25 publications

(13 citation statements)

References 4 publications

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“…These findings are in agreement with previous re ports which indicated that regional vascular changes occurred in the guinea pig uterus during early pregnancy [4,8,9,13] and were associated with regional differences in uter ine vascular pressure [14] and flow rates [8] in late pregnancy. The consistent elevation in blood flow to the tubal and cervical re gions of the uterus mimic growth patterns of the guinea pig fetal-placental unit, in which thé middle uterine zones consistently demon strated the lower weight and size parameters of the three uterine zones [8,14].…”

Section: Discussionsupporting

confidence: 93%

Uteroplacental Vascular Perfusion and Blood Flow during Pregnancy in the Guinea Pig

Garris¹

1984

Neonatology

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The relationships between regional uterine blood flow (UBF), placental blood volume (maternal compartment) and fetal-placental weights and size were determined at specific gestational stages in the guinea pig. Regional variations in UBF were noted between days 27 and 65 of pregnancy (day 0 = ovulation), with the tubal third of the uterus receiving a greater flow rate than the cervical region. The middle portion of the uterus consistently received a lower UBF than did the tubal or cervical zones. Between days 35 and 50 of gestation, UBF rates were consistently lower in the middle portion of the uterus as compared to the tubal and cervical regions in animals possessing exactly three pregnancy sites in a cornu. In contrast, placental blood volume in the maternal compartment from each of the three uterine zones was quantitatively similar, even though lower placental and fetal weights were found in the middle pregnancy sites as compared to either the tubal or cervical zones. When vascular perfusion rates were calculated by determining arterial-venous flow rate differences, both the tubal and cervical uterine zones were found to be preferentially perfused as compared to the middle uterine zone. These studies demonstrate that the correlation between regional UBF rates and fetal-placental development in the guinea pig is primarily due to the greater perfusion rate through the tubal and cervical zones of the pregnant guinea pig uterus, and not due to an expanded vascular volume of the placentae in these zones.

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Section: Discussionsupporting

confidence: 93%

Uteroplacental Vascular Perfusion and Blood Flow during Pregnancy in the Guinea Pig

Garris¹

1984

Neonatology

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“…Emrys-Roberts [ 13] postulated that endometrial areas rich in essential nutrients would induce the blasto cyst to implant in selected areas by attracting the pseudopodia which he believed func tioned in nutrient 'assimilation'. Bacsich and Wyburn [25] described a localized miduterine hyperemia which was under ovarian con trol and was believed to be associated, or favored, for implantation site selection by the blastocyst. It has also been noted that the preimplantation guinea pig blastocyst often aligns itself directly over a subepithelial cap illary plexus [21] much like that observed to occur in the rabbit [26].…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural Aspects of the Appositional Stage of Interstitial Blastocyst Implantation

Garris¹

1984

Gynecol Obstet Invest

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The ultrastructural aspects of the appositional phase of interstitial blastocyst implantation in the guinea pig have been investigated using scanning and transmission electron microscopy. Blastocysts measured 28–34 µm in diameter and were encased in the zona pellucida. Trophoblast pseudopodia which penetrated the zona made contact with the underlying uterine epithelium and served, along with uterine epithelial contact with the zona, to hold the blastocyst over the subsequent site of implantation. Pseudopodia emanated from the embryonic pole of the blastocyst measured 2–4 µm in diameter and initiated uterine-blastocyst contact. Pseudopodia contained a cytoplasm rich in tubular mitochondria, rough endoplasmic reticulum, and Golgi apparatus and usually were found directed toward a sub-epithelial capillary plexus. These results suggest that the trophoblast pseudopodia are very active metabolically and may serve to align the blastocyst over stroma regions possessing a rich subepithelial vascular supply and high nutrient availability.

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“…Previous reports suggested that localized, hyperemic areas of the uterus are best suited to support nidation since they would expectedly have a higher concentration of nutrients essential for fetal-placental viability [1,4,8], Support for this concept was evidenced by the fact that implantation sites in the rat have a greater vascular volume than do interimplantation regions [6], Evidence for a similar alteration in the guinea pig uterine vasculature has not been reported. The present study indicates that regional variations in UBF do appear soon after nidation (i.e., day 10) and persist at least through early gestation (i.e., day 20).…”

Section: Discussionmentioning

confidence: 99%

“…Alterations in these uterine vascular parameters were demonstrated to be regulated by various vasoactive agents, especially ovarian steroids [8] and adrenergic com pounds [2]. The functional implications of these changes remained obscure, although the similar timing of uterine hyperemia and blastocyst implanta-tion lead to the hypothesis that uterine vascular changes may be associated with pregnancy site selection in this species [1,7,8]. It was reasoned that the uterine sites possessing an enriched blood supply would best be able to support the nutrient requirement of the implanting blastocyst and develop ing fetal-placental unit [8].…”

Section: Introductionmentioning

confidence: 99%

Regional Variations in Uterine Blood Flow in the Guinea Pig: Relationship to Pregnancy Site Distribution

Garris¹,

Blankenship²,

Whitehead³

1983

Gynecol Obstet Invest

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The alterations which occur in the total uterine blood flow (UBF) during early pregnancy in the guinea pig were determined using electromagnetic blood flow probes. Between days 4 and 6 postcoitum, UBF rose from basal levels of 1.2 ml/min to peak levels of 3.0 ml/min. The elevated levels corresponded temporally with the onset of blastocyst implantation. Between days 7 and 8, UBF declined to basal levels. In guinea pigs possessing three pregnancy sites per uterine horn on days 10–20, obvious regional differences in UBF were observed. Consistently higher UBF measurements were monitored from uterine segmental arteries supplying the tubal and cervical thirds of the uterus than from those distributed to the middle third of the uterus. These data indicate that regional variations in UBF exist in the guinea pig which may be involved in the regulation of pregnancy site selection or subsequent placental-fetal growth.

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II.—Cyclic Variations in the Vascular Architecture of the Uterus of the Guinea Pig

Cited by 25 publications

References 4 publications

Uteroplacental Vascular Perfusion and Blood Flow during Pregnancy in the Guinea Pig

Uteroplacental Vascular Perfusion and Blood Flow during Pregnancy in the Guinea Pig

Ultrastructural Aspects of the Appositional Stage of Interstitial Blastocyst Implantation

Regional Variations in Uterine Blood Flow in the Guinea Pig: Relationship to Pregnancy Site Distribution

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