Counterstaining improves visualization of the myenteric plexus in immunolabelled whole-mount preparations.

Immunocytochemistry has emerged as a powerful research tool in neurobiology. One of the widely used methods is an indirect fluorescence technique that uses FITC- conjugated IgG to visualise protein expression within tissues, but a major drawback of this technique is the high background fluorescence due to non-specific antibody binding. Gut innervation is complex and best visualized in three-dimensions in whole mount preparations.

Aberrations of the intrinsic innervation of the anorectum in fetal rats with anorectal malformations.

Background: Fecal accumulation, constipation, soiling, and incontinence are common sequelae after repair of anorectal malformations (ARMs) in children. It is believed that besides the abnormalities of sacral roots, certain inherent abnormalities of the myenteric plexuses may play an important role in the final outcome after definitive repair.

Methods: This study was conducted to investigate the distribution of neuron-specific enolase (NSE), vasoactive intestinal peptide (VIP), and substance P (SP)-100 neurotransmitters in the rectosigmoid and fistulous tract of the ethylenethiourea-treated rat with ARMs.

Abnormalities of the vertebral column and ribs associated with anorectal malformations.

Lumbosacral vertebral abnormalities are a common association of anorectal malformations (ARMs) and are one of the determinants of the eventual level of fecal continence that can be achieved. This study used a fetal rat model to investigate the spectrum of axial skeletal maldevelopment that may occur with ARMs. Time-mated pregnant rats received 125 mg/kg of 1% ethylenethiourea (ETU) (experimental group) or vehicle only (control).

Evidence that the notochord may be pivotal in the development of sacral and anorectal malformations.

Background/purpose: The notochord is known to organize normal development of central axial structures, such as the spinal cord, vertebral column, and anorectum, but its role in abnormal development of these organs has not been well documented. The current study has used Ethylenethiourea to induce anorectal malformations in fetal rats, allowing investigation of abnormalities of the notochord and their relationship to the axial structural abnormalities that occur.

Methods: Timed-mated pregnant rats were fed Ethylenethiourea by gavage on gestational day 10.

Clarification of the processes that lead to anorectal malformations in the ETU-induced rat model of imperforate anus.

Background: Ethylenethiourea (ETU) administered to timed-pregnant rats can induce anorectal malformations (ARMs) in about 80% of rat fetuses, thus providing an ideal animal model to study the embryogenesis of ARMs. The current study was undertaken to investigate the embryogenetic events that may be responsible for the development of ARMs in rats.

Methods: Time-mated pregnant rats were divided randomly into control and experimental groups.

Patterns of apoptosis during degeneration of the pronephros and mesonephros.

Purpose: The adult mammalian kidney is preceded developmentally by 2 primitive kidneys. We determine whether apoptosis is involved in the regression of these primitive organs and document its temporospatial characteristics.

Materials And Methods: Timed pregnant rats were sacrificed at 11 to 16 days of gestation inclusively.