Fetuin as a marker of cortical plate cells in the fetal cow neocortex: a comparison of the distribution of fetuin, alpha 2HS-glycoprotein, alpha-fetoprotein and albumin during early development.

Fetuin, alpha 2HS-glycoprotein (alpha 2HS), alpha-fetoprotein (AFP) and albumin have been shown to be present in some regions of the neocortex in two early stages of development of the cow brain using PAP immunocytochemistry. In the pre-cortical plate stage fibres of the primordial plexiform layer stained positively for fetuin. No staining was seen for albumin but plasma and cerebrospinal fluid (CSF) were positive for alpha 2HS and AFP. In the early cortical plate stage the strongest fetuin positive staining was seen in the earliest formed cells of the plate. alpha 2HS staining was much less intense but similar in distribution. The possible role of fetuin, or related glycoproteins, in cortical plate differentiation is discussed. Staining for AFP and for albumin was seen mainly in the ventricular zone and marginal zone fibres, and had a similar distribution and intensity for both proteins. Plasma and CSF stained for all four proteins. Tests showed some cross-reactivity between fetuin and anti-alpha 2HS and, to a much lesser extent, between antisera to AFP and albumin and antigens denatured by fixation.

An immunocytochemical demonstration of alpha 2HS-glycoprotein in the developing neocortex of the rat.

The presence of the plasma protein alpha 2HS-glycoprotein (alpha 2HS) has been demonstrated in the developing rat neocortex, using biotin-streptavidin immunocytochemistry. alpha 2HS was observed in the neocortex on embryonic day 20 but not earlier. At this age it was present in cells of the subplate and of the intermediate layer and in layer I anteriorly. Between postnatal day 5 and day 10 alpha 2HS-positive cells were found in greater number in various cortical layers and in fibres in layer I. At postnatal day 28 no alpha 2HS-positive cells or fibres could be found in the neocortex. alpha 2HS has been reported to be very closely related to fetuin which is a fetal plasma protein found in cells of the developing cortex in the sheep and the pig. It is suggested that these glycoproteins may be important in some aspects of early neocortical differentiation.

Proteins in cerebrospinal fluid and plasma of the pouch young tammar wallaby (Macropus eugenii) during development.

The concentrations of total protein and albumin in cerebrospinal fluid (CSF) and plasma of tammar wallaby pouch young (Macropus eugenii) from birth until leaving the pouch have been measured. Total protein in CSF increased from birth (about 240 mg/100 ml) to 15-20 days postnatal (about 400 mg/100 ml) after which it declined. Albumin showed a proportionately greater increase from around 40 mg/100 ml to over 130 mg/100 ml, followed by decline after 75 days. Total protein and albumin in plasma increased throughout the period studied. Other proteins identified in CSF and plasma were: fetuin, alpha 2-macroglobulin, transferrin, alpha-lipoprotein, beta-lipoprotein, immunoglobin G and fibrinogen. One protein was only present in early pouch young (up to about 40 days) and was presumed to be the tammar equivalent of alpha-fetoprotein.