Fetal hyaloid artery: timing of regression with US.

Abstract

Large-aperture, dynamically focused ultrasonic imaging permits noninvasive, anatomic study of the eye at the millimeter level in the second and third trimesters of pregnancy. The authors report their observations of the hyaloid artery in 210 of 219 fetuses examined with this technique. This vessel is seen in fetuses of 20 weeks gestational age or less and regresses spontaneously at the start of the third trimester. The 210 subjects included 100 who were examined at gestational ages of 16-32 weeks or more and 85 healthy fetuses and 25 with pathologic findings at birth who were examined at 34 weeks gestational age to term. The presence of the hyaloid artery in the mid third trimester was uncommon in healthy subjects (less than 1%) and was not seen in any beyond 29.9 weeks gestational age. However, in nine of the 25 fetuses with abnormalities (five with trisomy syndromes), the vessel was seen at 30.8-36.8 weeks gestational age. The temporarily delayed regression of the hyaloid artery may occur with trisomy 21 syndrome and other forms of retarded brain development.

The Human Hyaloid System: Cell Death and Vascular Regression

“…In the present study, the hyaloid system was well developed by 10 WG and vessel regression was clearly evident by 13±15 WG, the involution of the hyaloid was ®rst evident in the VHP and subsequently the branches of the TVL and PM, consistent with previous reports (Balazs, Toth and Ozanics, 1980;Birnholz and Farrell, 1988).…”

“…Cells lost during ontogeny characteristically undergo apoptotic cell death (Kerr, Wyllie and Currie, 1972). While regression of the hyaloid vascular system has been extensively investigated (Jack, 1972;Birnholz and Farrell, 1988;Lang et al, 1994), the mechanisms involved, particularly in human tissue, have not been elucidated.…”

Axial growth of the fetal eye and evaluation of the hyaloid artery:in utero ultrasonographic study

“…However, we were able to ®nd only one study describing the in utero regression of this embryonic artery (Birnholz and Farrel, 1988). Failure of the embryonic hyaloid vasculature to regress completely will result in a spectrum of congenital abnormalities referred to as persistent, hyperplastic primary vitreous (PHPV) (Smirniotopoulos et al, 1994).…”

Candida(Amphotericin-Sensitive) Lens Abscess Associated With Decreasing Arterial Blood Flow in a Very Low Birth Weight Preterm Infant

“…6 These observations corroborated findings of an earlier report in which complete hyaloid artery regression was observed between 30 and 32 weeks' gestation. 7 The timing of this developmental regression of blood supply to the fetal lens suggests a potential window for initiation of infection in the lens and vitreous when the lens is vascularized, followed by resistance to antimicrobial and immune cell penetration once the lens is avascular. In the case of the patient, we speculate that there are at least 2 possible explanations about the hyaloid artery system involution for the infected lens.…”

“…Once the hyaloid artery involutes, the TVL is then completely supplied by the long ciliary arteries. [5][6][7] We report a case of candidal endophthalmitis with lens abscess formation presenting initially as a cataract in a preterm infant at 30 weeks' postconceptual age. This case is unique because the infant developed the fungal cataract during systemic antifungal treatment.…”